This proposal aims to better understand the signal transduction process mediating EphA2 receptor activation to endothelial cell (EC) migration. EphA2 belongs to a new family of receptor tyrosine kinases (RTK) that plays a critical role in cell-cell interactions during development and disease. Studies from our lab demonstrate that EphA2 regulates tumor angiogenesis through modulation of EC migration and assembly. However, the signal transduction pathways that couple EphA2 activation to angiogenic responses are not well characterized. To identify EphA2-interacting proteins, I am currently completing screens using MBP-EphA2 pull-down coupled to mass spectrometry and the yeast two-hybrid system. I have identified several candidate EphA2-interacting proteins, including guanine nucleotide exchange factor Vav3, adaptor protein Nck2 and lipid phosphatase SHIP2. In this application, I propose to finish the screens and investigate the role of EphA2-interacting proteins, Vav3 in particular, and their downstream signaling pathways in angiogenic responses. Since the EphA2 receptor is upregulated in tumor endothelium, success in this project may contribute to the development of anti-EphA2 cancer therapies.